1. Field of the Invention
This invention relates to integrated circuit design and particularly to flue design for integrated circuits.
2. Description of Background
In general, routing programs have difficulty accessing pins when there are not many options for accessing that pin. A problem arises when routing an integrated circuit design with multiple metal layers and at least one level of hierarchy. The problem is that nets with wires on the upper planes of metal need to be able to connect to pins on the lower levels of metal. Subsequently, if there are a lot of pins in a small area and very few tracks available to access those pins a generic router will most likely be unable to access all of the pins. Modern automatic routing applications have trouble connecting to these pins when the wiring resources available above and around the pin are highly restrictive. The solution has been to give the router extra area to route in order to get to the pin. However, it is not always possible or desirable to provide this extra area.